There are several instances in which it may become desirable to introduce therapeutic agents into a human or animal body. For example, therapeutic drugs or bioactive materials may be introduced to achieve a biological effect. The biological effect may include an array of targeted results, such as inducing hemostasis, reducing restenosis likelihood, or treating cancerous tumors or other diseases.
Many of such therapeutic agents are injected using an intravenous (IV) technique and via oral medicine. While such techniques permit the general introduction of medicine, in many instances it may be desirable to provide localized or targeted delivery of therapeutic agents, which may allow for the guided and precise delivery of agents to selected target sites.
For example, localized delivery of therapeutic agents to a tumor may reduce the exposure of the therapeutic agents to normal, healthy tissues, which may reduce potentially harmful side effects. Similarly, therapeutic agents may be delivered locally to a diseased portion of a coronary vessel to reduce, halt or reverse the progression of a stenosis, or may be delivered to a diseased portion of the aorta in order to reduce, halt or reverse the progression of an abdominal aortic aneurysm.
Localized delivery of therapeutic agents has been performed using catheters and similar introducer devices. By way of example, a catheter may be advanced towards a target site within the patient, then the therapeutic agent may be injected through a lumen of the catheter to the target site. Typically, a syringe or similar device may be used to inject the therapeutic agent into the lumen of the catheter. The therapeutic agent then may exit through a port disposed in a lateral surface at the distal end of the catheter. Typical catheter systems that locally deliver a therapeutic agent are limited in that they may only deliver one therapeutic agent at a time into the tissue. Moreover, it may be difficult to deliver a therapeutic agent to different depths into the tissue, resulting in treatment of only a portion of the tissue, e.g., the intimal layer, with one type of therapeutic agent. If multiple therapeutic agents are desired, or one or more agents are intended to be delivered at different tissue depths, then multiple components may need to be sequentially removed and inserted to achieve this result.